The two D.C. police officers had just responded to a robbery at a house party and were back in their cruiser, idling at an intersection on U Street NW, when a motorcyclist slid ahead of them.

The helmeted driver glanced back at the marked patrol car and then raced ahead, running the red light. “What is this guy doing? He must be crazy,” the cruiser’s driver, Officer Jordan Palmer, said as he flicked on the rooftop strobe lights and took off after a modified Kawasaki that could reach top speeds of 147 mph.

That began an unauthorized pursuit over more than 30 city blocks that lasted just a few minutes and ended when Palmer’s partner, Officer Brian Trainer, shot the motorcyclist twice at the entrance to the Third Street Tunnel. The first bullet pierced Terrence Sterling’s neck, severing his spinal cord and killing the 31-year-old air-conditioning technician. Sterling, who was heading home to Maryland, had marijuana and twice the legal limit of alcohol in his system.

The shooting of a black man by a white officer in the early morning hours of Sept. 11, 2016, sparked protests and worried D.C. leaders, as it came amid a growing distrust of police nationwide. A disciplinary hearing last week provided new details into what police officials say were several rule infractions, tactical mistakes and breakdowns by supervisors that ultimately led to the shooting.

The panel will now consider the evidence, and a decision could take weeks.

The incident, city attorney Nada Paisant told the police tribunal, began over “a traffic violation.”

Terrence Sterling, 31, of Fort Washington, Md. (N/A/Family Photo)

Paisant likened it to a road rage situation that the officers should have ignored. “Officer Brian Trainer and Jordan Palmer were pissed off they couldn’t effectuate a traffic stop,” she said at the hearing. “They were going to stop Mr. Sterling with whatever means necessary.”

Trainer testified that the motorcyclist — who had been reported recklessly driving at speeds exceeding 100 mph — purposely steered toward the cruiser after it pulled into an intersection ahead of the biker. The officer said he was climbing out of the car to make a traffic stop, while pulling out his gun, when the motorcyclist “violently” struck the open passenger-side door. Trainer testified that his right leg became pinned between the door and the car frame, and that while falling back into the seat, he fired twice through the open window “to relieve the pain.”

One of Trainer’s attorneys, Marc Wilhite, argued that the District had overblown the case because of “its notoriety,” noting protests and media coverage. “It is a false narrative that a white officer had an ax to grind against a black man,” Wilhite said. Trainer said he did not know Sterling’s race when he shot him.

D.C. Mayor Muriel E. Bowser (D) has said the police force can have no accountability with Trainer as a member. In February, the city settled for $3.5 million a wrongful-death lawsuit filed by Sterling’s family. Prosecutors reviewed the shooting but did not file charges.

But that did not end the case. The police department’s internal-affairs division in August declared the shooting unjustified, and officials recommended that Trainer be fired. Trainer appealed, prompting the hearing known as a trial board.

Such tribunals are typically public but attract little attention. This one spanned nearly 40 hours over three days and included testimony from a dozen witnesses, thousands of pages of reports and more than 1,500 photographs. A handful of demonstrators gathered the first day, although the public seats went largely empty.

The proceeding was a rare opportunity to witness a typically tight-lipped police department that carefully guards its internal workings, especially regarding discipline, engage in a brutal self-examination. District leaders had signaled early on that the shooting appeared troubling, in part because Trainer had failed to turn on his body-worn camera, depriving investigators of crucial evidence that has clouded a full accounting.

Trainer, 29, joined the force nearly six years ago and was assigned to patrol in the Third District, a diverse area that stretches from the elegant rowhouses of Kalorama through the bustling bars in Adams Morgan to ethnically diverse Columbia Heights and Mount Pleasant. He later joined a nightlife squad in Adams Morgan, where officers routinely deal with unruly bar patrons, and then went to the Crime Suppression Team, an elite group of police freed from answering routine service calls to prevent and confront violent crime.

The young officer had positive performance evaluations, earning “exceeds expectations” the year before the shooting, and colleagues described him as a calming influence. One recalled in testimony how Trainer once sprawled atop a bullet-wounded cabdriver to protect him as a gunman holed up in a nearby house.

But two captains and a commander who oversaw the hearing took turns grilling witnesses, sparing no one their frustration as they pointed to what they saw as instances where training, regulations and orders were ignored.

Panel member Capt. Robert Glover laid into Sgt. George H. Donigian Jr., a supervisor who saw the motorcycle speed by him on U Street, chased at 70 mph by Trainer and Palmer. Donigian and another sergeant in the car ordered the chase to end, but the officers carried on. Glover questioned what the supervisors did after their order was disregarded. Donigian, then six months into his supervisory role, answered: “I think we shook our heads and went back to our previous conversation.”

Cmdr. Morgan C. Kane, the panel chair, glared at the sergeant: “You are a supervisor. You must supervise your officers.”

The toughest pushback, both by the panel and lawyers with the D.C. attorney general’s office, fell on Trainer and his partner.

What Trainer and Palmer described as a “violent assault” by a motorcycle was to city attorneys a “tap” by a bike moving under 10 mph. Trainer’s “crushing injury” to his leg was characterized by the city as a scrape and a bruise.

Trainer said he didn’t even consider their actions a chase because he lost sight of the motorcyclist soon after the bike pulled away and didn’t clearly see it again until the final confrontation. Instead, he said, he and Palmer drove around “aggressively canvassing” for it.

The police officials overseeing the hearing deemed that term a euphemism to justify an unauthorized pursuit and questioned how Trainer planned to charge Sterling with reckless driving if the only infraction he saw was the red-light violation. Palmer previously had admitted to chasing Sterling against orders and was suspended for 20 days without pay.

The panel members and other officials also appeared incredulous at accounts from Trainer and Palmer that they barely talked as they sped through the city. “Unrealistic,” testified Assistant Police Chief Jeffrey Carroll, who chairs the department’s Use of Force Review Board and described the officers as using “very poor tactics.”

City attorneys said when the cruiser stopped at Third and M streets NW, the car improperly blocked the road. Trainer and Palmer testified that Sterling had room to maneuver around the car.

Palmer testified that he started to exit the driver’s side and planned to tackle or “take down” Sterling. Trainer said he had a different idea. He intended to stand in the street and order Sterling to stop, using his gun as an inducement.

Trainer said he planted one leg on the pavement. He said he yelled “Stop” or “You better stop.” Palmer said he heard his partner scream, “Get off the f---ing bike.” Trainer said the motorcyclist — 10 to 20 feet away, depending on witness testimony — revved the engine, turned the handlebars toward the officer and drove forward. “He was coming deliberately at me,” he testified.

Trainer said that he tried to retreat into the cruiser but that the motorcyclist’s tire hit the open door, trapping his right leg. He fired twice.

Trainer’s attorneys argued it was Sterling who put the series of events into motion. Kane blamed it on the officers’ actions. “How did we get all the way here for a red-light violation?” she asked at the end.